Abstract: A hybrid welding method of laser welding and arc welding for a T-joint in which a rib as one member to be welded abuts orthogonally onto a surface of a flange as other member to be welded includes forming a groove portion on a lateral surface of the rib that is an abutting part between the rib and the flange forming the T-joint; forming a flat part at a bottom part of the groove portion formed in the abutting part between the rib and the flange; and performing a hybrid welding using both laser welding in which the groove portion A with this flat part therein is irradiated with a laser beam, and arc welding, to form weld beads of weld metal in the groove portion A, so that welding together the flange and the rib forming the T-joint.

Abstract: The present invention provides a method of manufacturing a core shroud for a nuclear plant and a nuclear power plant structure in which a groove portion is easily assembled in the case of manufacturing the core shroud having a weld structure of a nuclear power plant by a laser welding, and it is possible to obtain a weld joint portion in which a plastic distortion region and a residual stress are as small as possible, going with a solidification shrinkage of the weld portion. At a time of welding butted portions of a plurality of members constructing a core shroud, a root face is provided in the butted portion, a length of the root face is set to 25% to 95% of a thickness of the thinner one of the butted portions of a plurality of members, a narrow groove is provided in the other than the root face, and the butted portions are welded by a laser welding using a weld wire.

Abstract: The present invention provides a method of manufacturing a core shroud for a nuclear plant and a nuclear power plant structure in which a groove portion is easily assembled in the case of manufacturing the core shroud having a weld structure of a nuclear power plant by a laser welding, and it is possible to obtain a weld joint portion in which a plastic distortion region and a residual stress are as small as possible, going with a solidification shrinkage of the weld portion. At a time of welding butted portions of a plurality of members constructing a core shroud, a root face is provided in the butted portion, a length of the root face is set to 25% to 95% of a thickness of the thinner one of the butted portions of a plurality of members, a narrow groove is provided in the other than the root face, and the butted portions are welded by a laser welding using a weld wire.

Abstract: An upper plate is arranged on the top surface of a lower vertical plate to form a T-type joint, and a penetration promoter is applied on the surface of the upper plate of the T-type joint. Subsequently, when performing non-consumable electrode arc welding, a penetration width w of a molten pool on the side of the vertical plate after penetrating through the back side of the vertical plate is formed equal to or greater than the vertical plate thickness if a lower vertical plate thickness is the same thickness as an upper plate thickness or thinner than the upper plate thickness, and the penetration width of the molten pool is formed equal to or greater than the upper plate thickness if the lower vertical plate thickness is thicker than the upper plate thickness, thereby forming a penetration shape having a desired welding metal part.